int zero() { return 0; }

int one() { return 1; }

int main() {
    int x;
    int y;

    x = zero();
    y = ++x;
    if (x != 1)
        return 1;
    if (y != 1)
        return 1;

    x = one();
    y = --x;
    if (x != 0)
        return 1;
    if (y != 0)
        return 1;

    x = zero();
    y = x++;
    if (x != 1)
        return 1;
    if (y != 0)
        return 1;

    x = one();
    y = x--;
    if (x != 0)
        return 1;
    if (y != 1)
        return 1;

    return 0;
}
